The automatic nervous system (ANS) regulates “involuntary” organs and maintains normal internal function and works with the somatic nervous system. The ANS includes the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system is affiliated with stress and the “fight or flight response” to emergencies, and the parasympathetic nervous system is affiliated with relaxation and the “rest and digest response.”
Autonomic balance reflects the relationship between parasympathetic and sympathetic activity. Autonomic balance may sometimes be referred to as autonomic tone, which refers to a background rate of activity of the ANS. Changes in autonomic balance are reflected in changes in heart rate, heart rhythm, contractility, remodeling, inflammation and blood pressure. Changes in autonomic balance can also be seen in other physiological changes, such as changes in abdominal pain, appetite, stamina, emotions, personality, muscle tone, sleep, and allergies, for example. It is desirable to monitor autonomic health as overall health depends on a healthy autonomic balance.